RE: [EE] Single Phase AC control via PWM (maybe a challenge?)

It's still a SMPS as the controlling element is operating in switch mode
not linear, certainly not phase control

I did propose a phase controlled very simple low cost solution which
seemed to fit most of his requirements 

He didn't even bother to comment 

Seems more intent on complaining how misunderstood he is.

I wonder if there is a hidden agenda

  PC

> -----Original Message-----
> From: piclist-bounces@... 
> [mailto:piclist-bounces@...] On Behalf Of Russell McMahon
> Sent: Monday, January 31, 2005 10:36 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Single Phase AC control via PWM (maybe a challenge?)
> 
> 
> Here we have several strong willed people (N against 1 - not usually 
> very fair) with good ideas talking past each other, failing to 
> understand what the other person has said, missing the good 
> points the 
> other has offered, being gratuitously rude to each other, incorrectly 
> criticising technical input from the other person and 
> generally having 
> a good time.

RE: [EE] Single Phase AC control via PWM (maybe a challenge?)

I did propose a phase controlled very simple low cost solution

Should have read

I did propose a phase control of a SMPS module 

> -----Original Message-----
> From: piclist-bounces@... 
> [mailto:piclist-bounces@...] On Behalf Of p.cousens
> Sent: Tuesday, February 01, 2005 12:52 AM
> To: 'Microcontroller discussion list - Public.'
> Subject: RE: [EE] Single Phase AC control via PWM (maybe a challenge?)
> 
> 
> It's still a SMPS as the controlling element is operating in 
> switch mode
> not linear, certainly not phase control
> 
> I did propose a phase controlled very simple low cost solution which
> seemed to fit most of his requirements 
> 
> He didn't even bother to comment 
> 
> Seems more intent on complaining how misunderstood he is.
> 
> I wonder if there is a hidden agenda
> 
>   PC

--

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[EE] Critique my project schematics

Hi guys, this is my first pic project and I'm hoping that some of you
would be kind enough to review my schematics for mistakes and blunders
and offer suggestions as you see fit. I don't have a background in EE
so this is designed with knowledge obtained from the list, internet
and some old electronics books.

http://www.geocities.com/mr_goat2000/schem.gif

The intent of this device is to control an electronic transmission.
There are inputs from a pressure sensor, thermistor and 6 switches as
well as the LM1815 chip which is meant for a variable reluctance
sensor. Outputs are to solenoids and the LM7221 which controls a 4
digit led display.

I have USART for debugging and possibly a bootloader in the distant future.

Do I have adequate decoupling for the automotive environment? Any
other comments, suggestions are welcome.

Cheers,
Milosz K.

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Re: [PIC]: Interrupt USART + TMR0

On Mon, 31 Jan 2005 23:14:01 +0100, Wouter van Ooijen <wouter@...> wrote:
> > No, I meant what I wrote.
> >
> > If the PID calculation was done in the background loop, there would be
> > a variable number of instructions between the setting of the DO_IT_NOW
> > flag and the start of the PID update.
> 
> I don't grok this. Which instructions would be inbetween? There are
> techniques to re-start a loop at fixed intervals, with zero jitter.

while (TRUE)
   {
    if (DO_IT_NOW)
      pid_calculations();
   code_a();
   code_b();
   code_c();
   code_d();
   }

since the DO_IT_NOW flag could be set at any time by
the interrupt (or the TMR1IF flag), the PID code could run
immediately, or after all the other routines, or...

Bill
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Re: [EE] Critique my project schematics

Hi,

The power supply is going to cause great problems in an automotive
design.  First off, your design should handle "load dump" (google it).
Your regulators are only good for 29volt input and in an automotive
system there are situations that can greatly exceed that limit.  You
will need some type of suppressor circuit.  Second, it would be
nice to have some sort of common mode choke in the supply to
remove noise.  A fuse would be nice as well.  The 12V supply
regulator won't have enough headroom when the ignition is off,
or when a transient occurs (like lights being turned on). You may
want to search around the net and look for good examples of
automotive power supply designs.

I didn't check the rest of the schematic.

Ken

klumia@...

----- Original Message ----- 
From: "Milosz Kardasinski" <miloszk@...>
To: "Microcontroller discussion list - Public." <piclist@...>
Sent: Monday, January 31, 2005 7:44 PM
Subject: [EE] Critique my project schematics

> Hi guys, this is my first pic project and I'm hoping that some of you
> would be kind enough to review my schematics for mistakes and blunders
> and offer suggestions as you see fit. I don't have a background in EE
> so this is designed with knowledge obtained from the list, internet

Re: [PIC]: Interrupt USART + TMR0

William Couture <piclist@...> wrote:

> while (TRUE)
>    {
>     if (DO_IT_NOW)
>       pid_calculations();
>    code_a();
>    code_b();
>    code_c();
>    code_d();
>    }
> 
> since the DO_IT_NOW flag could be set at any time by the interrupt
> (or the TMR1IF flag), the PID code could run immediately, or after
> all the other routines 

    ... and the only alternative to that code is to do everything
    inside the ISR? 

    Your issues, Bill, seem to be with a particular(ly bad)
    IMPLEMENTATION of an architecture, not with the architecture
    itself.  It isn't impossible to make your pid_calculations() code
    run always at a fixed time after the DO_IT_NOW flag was set; it
    just takes a little more creativity or experience or whatever.

    -Andy

=== Andrew Warren -- aiw@...
=== Principal Design Engineer
=== Cypress Semiconductor Corporation

Re: [EE] Single Phase AC control via PWM (maybe a challenge?)

> It's still a SMPS as the controlling element is operating in switch 
> mode
> not linear, certainly not phase control

It's a SMPS by basic definition ie SWITCHED mode power supply.
BUT it differs from what people almost always MEAN when they say SMPS.
SMPS means to most a device that uses reactive storage as a means of 
transferring energy at one impedance level to another impedance level. 
eg High voltage low current to lower voltage higher current.
His is EFFECTIVELY a resistive switch. ie it does not transform the 
energy to a different impedance level by storing it in a reactive 
element and then using the element differently. Instead it JUST chops 
the input voltage to decrease it. Iin to the switch block = Iout.
By that measure it is not a SMPS as we usually understand the term.
It suffers the large disadvantage of needing a conventional main 
transformer as well as a switch. This disadvantage is accepted by some 
in exchange for the advantages.

> I did propose a phase controlled very simple low cost solution which
> seemed to fit most of his requirements

He isn't really after a phase controlled solution - that is an 
unfortunate terminology which he probably picked up from others using 
the technique. The waveform is chopped multiple times per phase, not 
once only per half cycle as in traditional techniques. The method has 
several advantages over conventional phase control.

> He didn't even bother to comment
> Seems more intent on complaining how misunderstood he is.

Re: [EE] Single Phase AC control via PWM (maybe a challenge?)

Hi-

Well, if we can do this then can we also discard the transformer, pass 
the reduced voltage AC through a full-wave rectifier and get controlled 
DC?  I guess the downside is that there is no isolation.  Is adding 
isolation with a 1:1 transformers, and are they  cheap? 

David

Russell McMahon wrote:

> Here we have several strong willed people (N against 1 - not usually 
> very fair) with good ideas talking past each other, failing to 
> understand what the other person has said, missing the good points the 
> other has offered, being gratuitously rude to each other, incorrectly 
> criticising technical input from the other person and generally having 
> a good time.
>
> Why not start again and try a little harder. All can learn from this 
> technically ( if not socially  )
>
> Bob may yet learn that SMPS is not a total swear word and that what he 
> is proposing has SOME similarities.
> And 'we all' may realise that Bob is proposing a not new but less 
> familiar technique which may be very useful on occasion and which is 
> being used extremely successfully in some large real world applications.
>
> A confusion is that bob has used the term "phase control" consistently 
> when it's not phase control as our mothers understood the term. The 
> method simply consists of PWMing an input (usually mains) 50/60 Hz AC 

[OT] Subaru 360 Drivers Club - Yee Ha !!!

Brings back memories.
Some good.

        http://www.geocities.com/MotorCity/Garage/5360/main.html
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Re: [PIC]: Interrupt USART + TMR0

On Mon, 31 Jan 2005 17:30:30 -0800, Andrew Warren <aiw@...> wrote:

> It isn't impossible to make your pid_calculations() code
>run always at a fixed time after the DO_IT_NOW flag was set; it
>just takes a little more creativity or experience or whatever.

Feel free to enlighten us with your splendid code.

Bill
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